On Tue, Jul 01, 2003 at 04:46:55PM -0700, Joshua Oreman wrote: > On Tue, Jul 01, 2003 at 06:30:13PM +0000 or thereabouts, george donnelly wrote: > > hi > > > > I've got a 4.7 freebsd machine and after upgrading from 4 to 6GB of RAM, top > > does not recogmize the other 2 GB (only shows 4) and actually there was a > > message that said "ignoring 2 GB". > > > > Can anyone shed light on this or suggest where i can look to understand > > this? > > AFAIK, on i386 the maximum addressable memory space is 4096 MB. > Here's why: > C pointer = 4 bytes = maximum value 4294967296
Yes and no. i386 addresses are indeed 32 bits which means that a process can only address 4GB worth of memory. On the Pentium Pro and later x86 CPUs there some special tricks that can be used to have a physical address space of 36 bits (64 GB memory), even though a single process still only can use 4 GB. FreeBSD 4.x and earlier does not have any support for those tricks so it cannot use more than 4 GB of RAM. FreeBSD 5.1 and later does have support for PAE (Physical Address Extension) so it can handle up to 64 GB RAM (while a single process is still constrained to a 32-bit address space.) -- <Insert your favourite quote here.> Erik Trulsson [EMAIL PROTECTED] _______________________________________________ [EMAIL PROTECTED] mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to "[EMAIL PROTECTED]"
